Pliers are to be understood as such pliers being used to process a workpiece. The pliers include a pliers head including tools enabling the processing of the workpiece due to an application of pressure or of a movement. The pliers may be pliers for crimping workpieces to connect a connector to a partially bare end of a conductor. It is also possible that the pliers are working pliers with which a workpiece is permanently deformed, or a portion is separated from the workpiece, for example by punching. The invention relates to a positioning device especially serving to receive and to position the workpiece with respect to the two part tool being arranged in the pliers head. The invention especially relates to positioning relatively small workpieces for which a manual positioning movement through the opening of the pliers head with respect to the movable tool element is difficult or even impossible. Especially in case of crimping connections, the connector and the bare end of the conductor each have to be brought to a certain relative position with respect to the tool elements. In this case, the tool elements are designed as crimping dies. Usually, one portion of the die is stationary with respect to the pliers head, whereas the other tool element is movably guided in a linear direction, on a circuit or in a different way.
Pliers are known from German Patent Application No. DE 27 18 165 A1. The pliers include a pliers head having a C-shaped design, i.e. the pliers head is laterally opened. In a different embodiment, the tool elements are moved with respect to one another in a scissors-like movement. In both cases, a pliers head plane is defined by the pliers head, the pliers head plane being the middle plane of the direction of main extension of the pliers head. The pliers include a positioning device being pivotable about a pivot axis or a pivot bearing being arranged at the pliers head. The positioning device can be pivoted from an insertion position to a working position. The positioning device includes at least one receiving element to receive a workpiece. The pivot bearing of the positioning device is arranged with its pivot axis to extend perpendicularly to the pliers head plane. In this way, it is possible to pivot the positioning device in the insertion position, to insert the workpiece into the receiving element and to pivot the positioning device with the inserted workpiece through the opened side of the pliers head in the working position in which the workpiece has the desired relative position with respect to the tool. The processing of the workpiece may be effected by actuating the drive of the pliers. The drive is designed as two handles being pivotable with respect to one another. Thus, the movement is transmitted to one tool element travelling through a working stroke with respect to the other tool element. In this way, for example, a connector can be deformed.
It is disadvantageous that a connector can be only inserted into the pliers head in case the pliers head is open at one side. In case of annularly closed pliers heads, this positioning device is not applicable. Due to the pivot movement of the positioning device on a circuit, the number and the arrangement of the nests inside the tool is limited due to the pivot radius to be kept free. The pliers including the known positioning device only include one receiving element being arranged at the positioning device, and consequently, only one nest being arranged at the tool. Although it is possible to mount the workpiece onto the positioning device in the insertion position, the clearance being provided for the mounting movement is limited. Since especially a very small workpiece has to be inserted into the correct receiving element, or it has to be put onto a projection by handling the workpiece manually, the handling gets more difficult due to the limited clearance between the pliers head.
Similar pliers are also known in the art. The pliers include a pliers head having a plate design, the pliers head having a C-shaped design, i.e. the pliers head is laterally open. The pliers head defines a pliers head plane being the middle plane of the direction of main extension of the pliers head. These known pliers include a positioning device being pivotable about a pivot axis of a pivot bearing being arranged at the pliers head to be pivoted from an insertion position to a working position of the workpiece. The positioning device at least includes one receiving element for receiving a workpiece. Usually, the positioning device includes two receiving elements being arranged at the positioning device and two processing locations being arranged in the pliers head, i.e. a two part tool having two processing nests which are, for example, allocated to different diameters of workpieces. The pivot bearing of the positioning device with its pivot axis is arranged to be located perpendicularly to the pliers head plane. In this way, it is possible to pivot the positioning device towards the insertion position, to insert the workpiece in the correct receiving element and to pivot the positioning device with the inserted workpiece through the open side of the C-shaped pliers head into the processing position in which the workpiece has the desired relative position with respect to the tool. The workpiece can be processed by actuating the drive of the pliers. The drive may be designed as two handles being pivotable with respect to one another, as hydraulically or pneumatically biased piston, or the like. In this way, the movement is transmitted to one of the tool elements travelling through a working stroke with respect to the other tool element. For example, a connector can be permanently deformed. Before the actual working process is effected, it is possible and it makes sense, in connection with the connector, to position the partially bare conductor with respect to the pliers head perpendicularly to the pliers head plane from the other side of the pliers head at which the positioning device is not located. Thus, the conductor gets into its desired relative position with respect to the tool, and the connector and the conductor can be connected in the working process. After the working process, the pliers are opened, and the workpiece, for example the conductor with the connector crimped thereto, is unloaded. To start a new working operation, the positioning device is pivoted in the insertion position, and the operation is repeated.
It is disadvantageous that a connector can be only inserted into the pliers head in case the pliers head is open at one side. In case of annularly closed pliers heads, this positioning device is not applicable. Due to the pivot movement of the positioning device on a circuit, the number and the arrangement of the nests inside the tool is limited due to the pivot radius to be kept free. The pliers including the known positioning device only includes one receiving element being arranged in the positioning device, and consequently, only one nest being arranged at the tool. Although it is possible to mount the workpiece onto the positioning device in the insertion position, the clearance being provided for the mounting movement is limited. Since especially a very small workpiece has to be inserted into the correct receiving element, or it has to be put onto a projection by handling the workpiece manually, the handling gets more difficult due to the limited clearance between the pliers head.
Other pliers of the applicant of the type CS20KS are known. The pliers include a C-shaped pliers head being open at one side. At the pliers head, a positioning device is linearly guided on an axle being connected to the pliers head. The axle is arranged in a plane parallel to the pliers head plane. The positioning device is driven by a pivotable handle being arranged at the pliers head. Thus, the positioning device can be linearly moved in the insertion position in which the positioning device is located in front of the opening of the C-shaped pliers head. The linear movement of the positioning device is directed in the direction of the arrangement of the two part tool in the pliers head, and it ends in the processing position in which an inserted workpiece takes its correct relative position with respect to the tool inside the pliers head. This known positioning device is only applicable in combination with a C-shaped, laterally open pliers head, but not in case of annularly closed pliers heads. Due to the linear guidance of the positioning device, a greater freedom results in the arrangement of the nests at the tool in the pliers head. The number and the arrangement of the nest is also comparatively less limited. The clearance around the positioning device in the insertion position is comparatively improved. Generally, these pliers having the linearly guided positioning device have the same disadvantages as the pliers in which the positioning device is pivotable about a pivot axis being located perpendicular to the pliers head plane.
Flat pliers to produce end portions at metallic tissue hoses are known from German Patent No. 725 284. The pliers include clamping jaws being guided parallel. The clamping jaws are separated to insert and to unload the workpiece and the portions of the workpiece, respectively. The first portions of the clamping jaws are each pivotable with respect to the pliers head plane by a pivot bearing. The pivot axis of the pivot bearing is arranged in a plane parallel to the pliers head plane. The flat pliers do not include a positioning device.